The present invention relates to disc drive systems. More specifically, the present invention relates to an apparatus for burnishing asperities or surface irregularities on a disc surface.
In data processing systems, magnetic disc drives are often used as storage devices. In such devices, read/write heads which are located on a slider (or an air bearing) are used to write data on or read data from an adjacently rotating disc. The head is located either above or under the disc and isolated therefrom by a thin film of air. The thickness of the thin film of air depends on the disc's rotational speed and the shape of air bearing surface. During drive operation, the fly height of the head continuously changes as the head pitches and rolls with the varying topography of the disc. If the quality of the disc or the read/write head is poor, occasional rubbing or sharp contact may occur between the disc and the head. Such contact may damage the head or the disc, or cause loss of valuable data.
With increasing magnetic recording density, the head fly height (or slider clearance) becomes lower and lower. In other words, the contact frequency between disc and head becomes larger. A fly height of as low as 0.7.mu." is currently used in magneto-resistance reading. To prevent damage to either the disc or head for such low slider clearance, it has been recognized that the surface of the disc should be very flat and free of any bumps.
Various attempts have been made to provide increasing assurance that undesirable contact between a head and a recording disc does not occur. Rigid manufacturing and quality specifications for both the recording disc and the head have been instituted. One such attempt in the disc industry is to glide test all discs. If a bump or asperity is found on the surface of the disc, the bump must be burnished out by a thermal burnishing air bearing.
The burnishing air bearing helps to produce the highest quality media at every level. Thus, there is a need to provide an efficient burnishing air bearing design which has high production yields, low to zero noise in the burnish process, and relatively flat fly heights with nearly zero roll.